Protecting device for electric circuits



N. J. CONRAD.

PROTECTING DEVICE FOR ELLCTRIC CIRCUITS. APPLICATION FILED MAR. 31. um.

2 SHEETS-SHEET l.

-l-atcnted Deu. 27, 1921.

N. 1. CONRAD. PROTECTING DEVICE FOR ELECTRIC CIRCUITS.

APPLICATION FILED MAR. 31.1917.

Patented Dec. 27, 1921.

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. P 16% m M 0 mm 8mm UNITED STATES PATENT OFFICE.

NICHOLAS J. CONRAD, OF CHICAGO, ILLINOIS, ASSIGNOR TO SCHWEITZER & CONRAD, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

PROTECTING DEVICE FOR ELECTRIC CIRCUITS.

' Specification of Letters Patent. Patented D60. 27, 1921.

Application filed March 31, 1917. Serial No. 158,815.

T 0 all whom it may concern:

Be it known that I, NICHOLAS J. CONRAD, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Protecting Devices for Electric Circuits, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to protecting devices for electric circuits.

In my copending application, Serial No. 151,068 filed February 26th, 1917, which has since eventuated into Patent No. 1,291,621 under date of February 18, 1919, I have described and claimed as an article of manufacture a switching unit for breaking the flow of current particularly in a high voltage line and have described and claimed a novel manner of employing the same for automatic or manual operation.

In the present invention I provide novel means for securing manual or automatic operation of the switching unit and more particnlarly for securing simultaneous operation of a number of switching units such for instance as upon the three phases of a three phase transmission line.

Further my invention aims to provide means for interrupting all three phases of the power circuit upon the occurrence of overload in any one phase.

In the accompanying drawings which form a part of the present specification I have illustrated an embodiment of my invention Figure 1 is a front elevational view of the switching unit;

Fig. 2 is an enlarged elevational view partly in section to show the interior working mechanism of the switching unit;

Fig. 3 is a diagrammatic elevation of an installation employing the switching unit shown in Figs. 1 and 2 with the necessary means for causing individual and simultaneous operation of the switching unit to open the power transmission line; and

Fig. 1 is an elevation partly in section of the manual means for operating the switchingunits.

The switching unit 1, as illustrated in deternally threaded ring 5. The lower section 2 is provided at its lower end with a metallic closing cap 3 which forms a terminal of the switching unit. A metallic cap 4: closes off the upper end of the upper sleeve section and forms another terminal. The metallic ring 5 lies at the junction of the sleeve sections and forms a third terminal. The sleeve 2 completely incloses a switch. The stationary cylindrical contact 6 of the switch is connected electrically to the ring 5 by means of the perforated web 13 and the movable member 7 of the switch is electrically connected to the lower cap or terminal 3. The movable element 7 of the switch is held against. the relatively stationary member 6 by a fuse 8 which is made of small capacity in order that it may readily be blown by the expenditure of a small amount of energy. The fuse 8 preferably consists of a wire of small diameter having high tensile strength and high specific resistance. This fuse is connected at its upper end by means of the screw 9 to a bridge member 10 which is formed upon the lower side of the cap member 41 on the interior of the sleeve 2. The cap member is provided with an opening which is normally closed by the removable'plu'g 11, this plug having a venting disk 12 secured by soft solder of low strength so that upon the occurrence of excessive pressure within the sleeve 2 this venting member 12 will be blown off and .will relieve the pressure within the sleeve 2. It is to be understood that the sleeve 2 is liquid tight and that a suitable arc extinguishing liquid (not shown) is in this sleeve 2 substantially filling the sleeve. For an arc extinguishing liquid I employ oil, carbon tetrachlorid or one of the liquids disclosed in a copending application Ser. No. 120,625, filed September 18, 1916, by myself and Edmund O. Schweitzer, which application has since eventuated into Patent No. 1,319,907 under date of October 28, 1919.

The stationary contact 6 is made in the form of a hollow plinder to obtain a large area of contact wi 11 the plug 7. The ring '7 and 6 and 5, the web 13 and the contact 6 are formed of a single casting. The web 13 is perforated as shown to permit the arc extinguishing liquid to pass between the two chambers particularly when the plug 7 and the liquid director 16 begin to move downward before the plug 7 is separated from the stationary contact 6.

The movable switch member 7 comprises a cylindrical contact which fits inside of the ring 6 being slitted as shown at 14 to provide a number of spring fingers for making a yielding contact with the ring 6.

The interior of the cylindrical contact member 7 is counter bored and a pin15 is screwed into the bottom of the bore to form a removable terminal for the fuse member 8. As will beexplained later =when the switch is opened the pin 15 is adapted to sustain the are so long as it exists. If the pin is damaged it may be removed and anew pin substituted.

The movable terminal member 7 is provided with a liquid director 16 which, as will be described later, is adapted to force a stream of the arc extinguishing liquid around the outside of the cylindrical contact 7 and through the slots 14 and the openings 17. The liquid director 16 is connected to the movable contact 7 by means of the trans verse pin '18; The movable contact 7 is connected 'to a spring 19 which is adapted to draw the movable contact 7 down into the liquid and to separate the switch elements project the arc extinguishing liquid into the space between them. The spring 19 is connected at its upper end to a pin or boss 20 formedon the lower end of the switch contact 7 and is connected at its lower endto the terminal cap 3. Suitable fiexibleconducting cables 21 are connected between the movable terminal 7 and the terminal cap 3 to prevent any possibility of damage to the spring 19 by flow of excess current. i

The switching unit thus far described is adapted to be mounted upon a suitable base or mountmg having spring contact members for engaging the members 3, 4 and 5. The cap 4, the ring 5 and the lower cap 3 are provided with respectively on each side for engagement of the spring mounting clips. The splays 4" prov de shoulders 22 which are adapted to engage the upper spring terminals and support the weight of the switching unit so that there is no tendency for it to drop down axially when the switching unit'is sus ended igs. 1

flat faces or splays 4 5" and 3*" in high voltage lines but may be employed under any desired conditions.

According to the present'inve-ntion the switching unit is connected with the switch 6, 7 included directly in the line. I

In Fig. 3 I have illustrated diagrammatically an installation for a three phase circuit employing the switching units designated individually as 23,24 and 25. The unit 23 is connected at the terminal cap 3 with the outgoing line wire 26 and at the terminal 5 with the incoming line-wire 27. The incoming line wire is provided with an overload coil 28 having a movable element, in this case the solenoid plunger 29 which is adapted to be attracted upon flow of excessive current in the wire 27, 26.

The fusible member 8 which normally holds the switch in closed position is connected in series with a normally open circuit 30.which has an independent source of current, as shown at 31, which may consist of a few cells of dry battery or of a storage battery. This battery is supported on the same insulator which supports the terminal clips that cooperate with the terminals 4 and 5. The'circuit is provided with a normally open switch 32 comprising the stationary contact 33 and the movable contact 34 which movable contact is connected as by means of the rod 35 to the solenoid plunger 29. The rod 35 is connected by means of a spring con-- nection 36 with the movable contact 34 for a purpose later to be described. It will be apparent from the above description of connections that when overload current passes through the line wire 27 26 which includes the switch 6,7 and the solenoid coil 28- serially, the plunger 29 will be raised closing the switch 32 thereby throwin the voltage of the independent source of current 31 across the fusible link 8 which is immediately fused and it in turn releases the movable switch member 7. The switch member 7 being free to move opens-the circuit at that point. It is desirable in a multiphase line to open all of the phases simultaneously, either in the normal switching operation or under overload or short circuit conditions. I have therefore provided means which will cause opening of all-of the phases of the line as indicated in Fig. 3.

The plunger 29 of the solenoid 28 is con-' nected by an insulated stem 38 to the plunger 39 of a low voltage solenoid 40. Each of the switching units 23, 24 and 25 is thus pro vided with a low voltage solenoid. These solenoids are bridged across the low voltage mains 41 and 42. A low voltage battery 43 such as a number of dry cells or a storage battery is connected between the low. voltage main 42 and another low voltage'main 44. The plunger 39 is connected to a switch 45 which has its stationary contact 46' connected to the main 41 and has its movable member 47 connected to the main 44. The

otherswitching units 24 and 25 are provided with similar low voltage switches 45' and A manually operable switch 49 is con nected between the low voltage main 41 and the battery 43 so that the battery may be bridged across the mains 41 and 42 for manual operation of the switching devices as by means of remote control. The switch 49 may 'beplaced at any convenient point for operating all of the switching units simultaneously.

The springs 36 and 48 permit relative movement between the rod 38 and the switch members 34 and 47 so as to insure proper closing of both of them by movement of the rod 38. It is apparent that either the stationary or movable contacts may be provided with yielding means to accomplish the same result.

The operation of the system is as follows During normal flow of current through the lines 27, 27? and 27 the main switch ,6, '7

remains closed, being held in place by the fuse member 8. This fuse member is not at this time subjected to any current fiow' and is therefore not liable to false operation. This is one important aspect of my invention and results from the fact that a separate source of current is provided for blowing the releasing element 8.

Upon the occurrence of excessive current flow the switch 32 will be closed by raising the solenoid plunger 29. At the same time the switch 45 will be closed. In fact the arrangement shown in Fig. 3 permits the switch .45 to close prior to closing of the switch 32 so that each of the plungers 39,

39 and 39 will be operated upon by the corresponding solenoid and as a consequence the switches 32, 32 and 32 will be closed substantially simultaneously. Closing of the switch 32 causes current to flow through thereleasing memberv 8 and as a consequence the spring 19 operates to open the main switch 6, 7. It is apparent that where it is desired manually to open the lines, this may be accomplished by closing the switch 49. Manual raising of one of the rods or plungers accomplishes the same result.

The solenoid 28 is a current responsive elementwhich operates upon overload to open the switching units. This element need not be connected directly in series with the line as it may be connected by a current transformer as will be readily apparent to those skilled .in the art, the definite relation to the current flow being the important consideration. This element may also be connected to operate upon a switch bridged across the mains 41-44 (like the switch 49) instead of operating through the rod 38. Such connection is electrical instead of mechanical. This permits of greater flexibility than having the element 28 operating directly upon the switch 32 and any desired type of relay connection may be employed as is well understood by those skilled in the art.

In Fig. 4 I have shown means for operating the switching units. This device comprises a box of insulation 110 mounted on' a rod 111 of insulation and containing a battery of a few dry cells 112. A pair of spring contacts 1'13114 are mounted on the side walls of the box 110 and these contacts are connected to the terminals of the battery. If it is desired to operate a switching unit the contacts 113114 are brought against the terminals 45 and as a consequence thefusible element 8 is melted and the switch 6-7 opened. This manual operating element may be employed to operate the switching unit in case the battery 31 should fail or in case the power should be off in the system shown in copending application, Serial No. 151,068. f I

The matter of securing simultaneous operation of the switching unit is an important aspect of this invention.

The feature of employing an independent source of current for operating the switching units individually and for operating them simultaneously is of importance par- I insufiicient current might be flowing-"co accomplish this result if the flow ozt current were depended upon to operate the fuse 8. In supplying independent sources of cur.- rent I make the switcheskoperable independently of the charged'or uncharged condition of the line. I v

v The same advantage accrues to the multiple operating circuits 41, 42 and 44 and no danger from the high voltage current exists.

I claim: y

1. In combination a switch adapted to interrupt a flow of current, means tending to open said switch, means restraining said switch, said latter means comprising a use and means comprising an independent source of current to cause a flow of current through said fuse sufiicient to melt the same.

2. In combination a switch of relatively large capacity, means tending to open said switch, means restraining said switch, said means comprising a fuse of relativelv small capacity, an independent source of low voltage currentpand means to connect said source of current. to said fuse to melt the same. 3. In combination a switch of relatively large capacity, means tending to open said switch, means restraining said switch, said means comprising a fuse of relatively small capacity, and; an independent source of low voltage current adapted to be connected in series with the switch-and said fuse.

4. In combination a line adapted to carry current, a switch of relatively large capacity in said line, means for opening said switch, a fuse of relatively small capacity, melting of said fuse being adapted to cause said switch opening means to operate and a source of low voltage current adapted to be connected across said fuse to melt the same.

5. In combination a switch, spring means tending to open said switch, means for holdingsaid switch closed, said means comprising a fuse of relatively small capacity and means for applying a current to said fuse independently of the main current flowing in said switch to blow said fuse.

6. In combination a current conductor, a switch in series with said conductor, means tending to open said switch, means for holding the switch closed, said-means comprising a fuse of relatively small capacity, a current responsive device in series relation with said conductor, a source of low voltage current, and means controlled by said current responsive device for connecting said source of low voltage currentacross the terminals of the fuse.

7. In combination, a high tension current conductor, a switch of relatively large (air cuit-breakingcapacity in series with said conductor, said switch comprising a relatively stationary and a relatively movable mem er, means for moving said relatively movable member, a fuse of small current carrying capacity and small break-down strength controlling said foperatin' means, said fuse being normally not sub ected to current flow, an independent" source of cur rent and circuit connections between the source of current and the fuse: v

8. In combination, an inclosed switch, said switch comprising a casing, a2 relatively movable and a relatively stationary terminal inclosed in said casing, spring means,

for moving the relatively movable member, a fuse of low capacity controlling said spring means, external terminals for said switch and for said fuse and a normally open low' voltage circuit connected to the terminals of the fuse.

9. In combination, a plurality of switches of relatively large capacity, said switches being adapted to be connected in series with a transmission line, means for opening each switch, independent means at each switch controlling the opening means, said independent means comprising a' fuse, an indi vidual source of current for each fuse and means for causing simultaneous connection BIS I,

of the current means to their respective fuses to open the switches simultaneously.

10. In combination a transmission line,

switching means connected in series in said i transmission line, a fuse of relatively small capacity for each switching means, said fuses governing the opening of said switching means, means for applying current to said fuses independently of the transm ssion line and means responsive to the current How in said transmission line for causing simul-.

taneous operation of each of the'switching means.

11. In combination a transmission line comprising a series of conductors adapted to" be connected to a common source of current supply, switch ng means in series in each of the conductors of said transmission line, means responsive to current flow in said transmission line, a current responsive elemeht' ofsmall capacity for each of the switching means for controlling the opening of said switching means, an independent source of low voltage current for each of said current responsive element, and means controlled by the current responsive means in the transmission line for causing simultaneous opening of said switching devices.

' 12. In combination a series of switching devices adapted to be connected in series with the conductors of a transmission line, fusible means of relatively small current carrying capacity controlling the opening of each switching device, an external switchfor each switching device for controlling the pendent of each other, individual inclosing members for inclosing the switching devices, a fuse in each inclosing member for holding the switching device in closed position, cur-. rent responsive means for each phase, independent switching means for each fuse and means controlled by last said switching means for blowing the fuse torelease the corresponding switching device, each switching means being controlled by the current responsive r device of the corresponding phase.

14. In combination a transmission line, a switchingdevice connected in SGI'IGS with each phase of the transmission line, said switching devices being mechanically independent of each other,individual inclosing 'means for blowing the fuse to release the corresponding switching device, each switching means being controlled by the current responsive device of the corresponding phase, and means controlled by operation 4 of the current responsive device of one phase for operating all of said switching means.

15. In combination a plurality of current conductors, switching means in series with each conductor, means tending to open said switching means,. means for holding said switching means in closed position said latter means comprising a fuse corresponding to each conductor, said fuses preventing the opening of said switching means and an independent source of current for causing simultaneous opening of the switching means of the plurality of conductors.

16. In combination a multiphase power ,line, a switching device in series in each phase, fusible means for each phase for pre: venting operation of the switching devices, an independent source of current for each fuse, switching means for Said sources of current to connect the same to the fuse, operating devices for said switching means and a multiple circuit for actuating each of said operating devices.

17. In combination a multiphase power line, a switching device in series in each phase, fusible means for each phase for preventing operation of the switching devices, an independent source of current for each fuse, switching means for said sources of current to connect the same to the fuse, operating devices for said switching means and a multiple circuit for actuating each of said operating devices, and current responsive devices for each dphase for controlling the operation of sai multiple operating circuit.

18. In combination a series of switching units, adapted to be connected in the phases of a transmission line, a current responsive device serially related to each phase, an independent source of current for causing operation of each switching unit, switching means controlledby the current responsive device of each phase for controlling the independent source of current and means connecting said switching devices to cause simultaneous operation of said switching, units.

19. In combination a normally closed switch of relatively large current carrying capacity, a controlling element for said switch of small current capacity for main taining said switch in closed position, and

an independent source of low voltage current for operating said element and automatic means depending upon the current flow in the switch for connecting said source of current to said element to operate the same.

20. In combination a high tension current conductor, a high tension circuit breaker in said conductor, a fuse of small capacity controlling said circuit breaker, and an independent source of current for blowing said fuse.

21. In combination a high tension current conductor, a high tension circuit breaker in said conductor, a fuse of small capacity controlling saidcircuit breaker, and an independent source of current for blowing said fuse, and automatic means serially related to said current conductor for control ling said source of current.

22. In combination, a switch of relatively large capacity, means tending to open said switch, means restraining said switch, said means comprising a fuse of relatively small capacity, said fuse being normally not sub-- ject to current flow, a source of low voltage current and means controlled by a predetermined maximum value of current in the line for connecting said source of current to said fuse to melt the same.

23. In combination, a switch of relatively large capacity, means tending to open said switch, means restraining said switch, said means comprising a relatively small capacity fuse normally not subject to current flow and a source of low voltage current adapted to be connected in series with the switch and said fuse to melt the same.

24:. In combination, a line adapted to have a normal flow of current, a switch mechani- 'cally retained in closed position, a fuse of small capacity holding said switch closed, means compr1sing a source of low voltage current for fusing said fuse, and means controlled by apredetermined maximum value of current in the line for connecting said source of low voltage current. across said fuse.

25. In combination, a switch of relatively large capacity, means tending to open said switch, means restraining said switch, said restraining means comprising a fuse of rela-. tively small capacity, said fuse being normally not subject to current flow, and an independent low voltagesource manually connectible with the fuse for melting same independently of, the charged or uncharged condition of the line.

26. In combination, a main switch, a fuse of small capacity, holding the switch closed, an independent source of low voltage cur rent for blowing the fuse and manually controllable means for connecting said source of low voltage current to said fuse to blow the same.

27. In combination, a line adapted to have a normal flow ofcurrent, a switch ofmeans controlled by a predetermined'maximum value in the line for connecting a source of low voltage current across said fuse to melt the same. 1(-

In Witness whereof I hereunto subscribe my name this 29th day of March, A. D. 1917.

NICHOLAS J CONRAD. 

